why all of a sudden am I seeing: FORBIDDEN You don't have permission to access / on this server.

I can normally access Firefox with no problem. Now when I try to connect to Firefox I see an error message that says: FORBIDDEN You don't have permission to access/on this server. What's up with that? How do I fix it?

I can normally access Firefox with no problem. Now when I try to connect to Firefox I see an error message that says: FORBIDDEN You don't have permission to access/on this server. What's up with that? How do I fix it?